For a long time my rent collection process was: check the bank app around the first of the month, scroll for the deposit, assume it's fine if I see something that looks about right. That's not really knowing. That's a glance and a guess dressed up as confidence.
The gap between "I think they paid" and "I know they paid, this amount, on this date, and here's the record" doesn't matter until it matters a lot. It matters when a tenant disputes a late fee. It matters at tax time, reconstructing a year of payments from bank statements and memory. It matters when you're trying to figure out if a tenant who's been late twice is actually a pattern or a coincidence, and you can't remember without digging.
Knowing means every payment is a record tied to a tenant and a property the moment it happens, not a transaction line you'll interpret later. It means you can answer "has this tenant ever paid late before" in five seconds instead of scrolling back through months of statements.
It also means the late ones surface themselves. Instead of noticing a missed payment because you happened to check, the ledger just shows you who hasn't paid, the same way it shows you who has.
You shouldn't have to be the one keeping rent collection straight in your head. That's exactly the kind of fact a piece of software should just already know.